Necrosis and angioinvasion predict adverse outcome in pancreatic neuroendocrine tumors after curative surgical resection: results of a single-center series.

Background: The prediction of outcome in pancreatic neuroendocrine tumors (P-NETs) still represents a challenge. Several clinicopathologic parameters have been proposed to predict adverse outcome. The aim of this study was to evaluate the impact of tumor necrosis and angioinvasion on the outcome after curative R0 resection of P-NETs.

Methods: We reviewed our institutional experience over the last 30 years. A total of 82 patients with a mean age of 54 years (range 17-83 years) underwent surgical resection of P-NETs during the period from 1964 to 2006. There were 41 men and 41 women. The patients' outcomes after R0 surgical treatment were analyzed in relation to the presence or absence of tumor cell necrosis and angioinvasion as judged by histologic methods.

Results: The overall (n = 82) 5-year survival was 52.4% (± 6.0%). Forty-eight of the patients underwent a R0 resection successfully. These patients showed a 5-year survival of 59.04% (± 7.8%); the median survival was 101 ± 36 months. Necrosis status was documented on 47 of the R0 resected patients (97.9%). The survival median of patients with tumor cell necrosis was significantly shorter than those without necrosis (41 ± 25 vs. 173 ± 69 months, respectively, P = 0.006). The patients' mean 5-year survival was also significantly decreased (28.9 ± 15.0% vs. 68.5.6 ± 8.9%). Angioinvasion status was documented on 43 of the R0 resected patients (90.0%). The median survival of these patients was decreased from 173 ± 51 to 54 ± 18 months when angioinvasion was observed in the histological sections (P = 0.104). The patients' mean 5-year survival was also decreased from 69.2 ± 9.3% to 35.9 ± 14.0%.

Conclusions: Long-term survival of patients with P-NETs is influenced by various pathologic factors. Among our patients, there was not a significant difference in overall survival based on the diameter of the primary tumor or the lymph node status after R0 surgical resection. The presence of necrosis in the TNM and World Health Organization classification for pancreatic endocrine tumor was associated with significant poor overall survival in each classification category. Hence, necrosis represents an independent variable for poor prognosis.